1. Field of the Invention
This invention relates to a novel organic silicon compound having a hydrogen atom directly attached to a silicon atom (or a silylidyne .tbd.SiH group) in a molecule and a fluorinated group at either end, which is useful as a crosslinking agent for various resins. It also relates to an organopolysiloxane composition which is readily curable to products having solvent and moisture resistance and thus suitable for use as electronic part encapsulants, sealants and coating agents.
2. Prior Art
Heretofore, addition curing type silicone compositions have been used in a variety of fields. These silicone compositions cure by crosslinking through hydrosilylation reaction represented by the following reaction scheme. ##STR1## In this reaction, the siloxane having a .tbd.SiH group is used as a crosslinking agent. Illustrative examples of the siloxane used are given below. ##STR2##
However, when the above-mentioned crosslinking agent is blended in a fluorinated silicone composition having a high fluorine content, the resulting composition is less curable because the agent is incompatible with the composition. Additionally, according to our finding, the composition has another drawback that it lacks adherence. Even when a tackifier is further added to the composition, a cured product obtained therefrom hardly adheres to various substrates.
It was recently proposed to improve compatibility by using as a crosslinking agent a silylidyne (.tbd.SiH) group-containing siloxane compound having a fluorinated group in a side chain represented by the following general formula. ##STR3##
In the formula, Rf is a fluorinated substituent selected from groups of the following formulae: ##STR4##
wherein m is an integer of 1 to 4, n is an integer of 1 to 6 and j is an integer of 1 to 12.
This siloxane compound, however, is difficult to provide an organopolysiloxane composition which is effectively curable into a well adhesive product because the Rf group in the side chain has steric hindrance to the .tbd.SiH group. Therefore, it is desired to overcome these problems of curable organopolysiloxane 1.5 compositions.